In movies and hows about steath aircraft they always say how it's "radar signiture is reduced to the size of a small bird" isn't it easy to proram a radar to detect a small bird moving at 100mph + and designate it as a hostile ?

isn't it easy to proram a radar to detect a small bird moving at 100mph + and designate it as a hostile

It is not technically difficult in free ECM environment and to detect at medium altitude as it is mainly a question of power output and receiver sensitivity.Some radar use to track ICBM in test can detect a golf ball at thousands km.

But not normal existing air defense radar.

However stealth target detection is greatly enhanced by networking as you can tolerate a bigger false alarm rate and remove false targets by merging data from different radars.

as FS said it shouldn't be that hard if you have a clean environment. if you start talking about a combat environment you have to realize that isn't clean. active jamming will limit radar's effectiveness as well as active use of anti radiation missiles will remove some of your detection capability. if you start removing filters then you might be able to see some stealth aircraft but you may also be making mistakes and attempting to shoot down stuff that is not there which is not good when you have a limited number of assets to attack the enemy. weather would also effect your radar to some point. many other things will also limit the ability of a radar to find stealth aircraft.

Now not sure how this technology works, but what if a MAD detector is used as well ? a computer program then then decide which small bird is containng tons of metal and which isn't therefor being able to designate which is an enemy aircraft and hwich is just ghost images, missles, or birds.

As a practical matter against our threat nations, yes it is hard even in an environment without jamming. In the first place, many of their early warning radars aren't sensitve enough to detect our stealth aircraft above the noise at all. The rest of the threat radars have detection ranges measured in tens of kilometers when looking at targets of -30dBm and smaller. At mid to high altitudes, particularly for the F-22, even these remaining threat radars have little capability as most of them have a narrow range band between initial detection and when the jet is at too high an elevation angle and altitude (it's actually *too* close in the horizontal plane) for continued tracking. Very few of our threat nations have the resources to blanket their airspace with enough early warning radars to cover it adequately. And then there are the initial attacks against the air surveillance network that opens holes in what little coverage they have, and then there is jamming of what radars are left....

Im told airframe shape on the F117 was optimised for a particular Radar operating frequency range (Not to sure about the B2) now Legend has it that rapier coud track the F117 as the frequency it operated at was not one scattered by the airframe - goes into faceting and wave lengths but i will spare you details (mainly because its a deep puddle and id rapidly get out of my depth). obviously im not in a position to know if this is 100% kosher but is i think plausable.

Heat signature is another potential tracking method although the likes of the B2 does its best to minimise this